Abstract Refluxing 3-amino-2-iminonaphtho [1, 2-d] thiazole (1) with diethyl oxalate (2a) in a 2: 1 molar ratio in dry pyridine provided 2, 2′-binaphtho [1′, 2′: 4, 5] thiazolo [3, 2-b][1, 2, 4] triazole (3). On the other hand, when 1 was treated with excess amount of 2a in dimethylformamide, it afforded ethyl naphtho [1′, 2′: 4, 5] thiazolo [3, 2-b][1, 2, 4] triazole-2- carboxylate (4a) on heating and ethyl N-(2-iminonaphtho [1, 2-d] thiazol-3-yl) oxamate (5) ...